The described aspects relate generally to wireless communication systems. More particularly, the described aspects relate to techniques for cell update message management.
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks. Furthermore, UMTS supports multiple radio access bearer (multi-RAB) capability, which allows simultaneous network communication with a user equipment (UE) over two or more radio access bearers. Therefore, in an aspect, multi-RAB functionality in UMTS allows for a UE to concurrently transmit and receive packet-switched (PS) and circuit-switched (CS) data.
When a UE operates in communication with a network, the UE may receive a security mode command that triggers a process to reconfigure security related parameters. The process to reconfigure security related parameters may be referred to as a security mode procedure or simply a security procedure. During the security mode procedure, a Radio Resource Control (RRC) layer of the UE may configure other lower layers with the reconfigured security related parameters and may send a Security Mode Complete message to the network when the security mode procedure is complete. The network may respond to the Security Mode Complete message with an acknowledgement message. If a cell update procedure is triggered before the UE gets the acknowledgement message from the network in response to the Security Mode Complete message, the UE may have to abort the ongoing security mode procedure and continue with the cell update procedure as if the security mode command had not been received. Since the network does not have knowledge of whether the UE has reconfigured the security related parameters, the network and the UE may not be synchronized as to the current security status of the UE. To address this issue, a new information element (IE), e.g., “Security Revert Status Indicator,” may be included in a cell update message to indicate the security status of the UE and whether the UE has applied the new security configuration provided in the security mode command.
However, a cell update message may not be transmitted to the network from the UE if the size of the cell update message is greater than a transport format size determined in the 3GPP specification. With the inclusion of the Security Revert Status Indicator IE, and perhaps the inclusion of other IEs as well, the size of the cell update message may be greater than the transport format size, which may impact whether the cell update message can be sent by the UE to the network in accordance with current communications protocols.
Therefore, there is a desire for techniques for managing information elements in a cell update message to facilitate the transmission of the cell update message from the UE to the network.